Budget flash for A550

I've been enjoying photography on a tight budget with A330, various minolta lenses and Sony HVL-F20M flash. Recently I had a chance to 'upgrade' to a mint A550, which has been an awesome improvement over the A330. I was hoping to get a more versatile flash to go along with this body, without paying more than $100. (I got the body for $60...)

Unfortunately, after couple hours of research, I'm at a loss as to what would be a good option. I didn't realize Sony changed shoe mount in 2012, and most of the inexpensive new flashes from Neweer or Godox seem to target all the other brands and the new Sony shoe. I can't find any comprehensive guide to newer third party flashes, while the older flashes are hard to come by. It seems impossible to get a used Minolta 5600HSD for less than $100.

So I was wondering, what are decent budget options for a decent flash for my A550? Would getting an adapter for iISO mount to Nikon/Canon/new Sony and getting one of the Neweer or Godox TT685S work? I'd like to use it as both on (with TTL) and off-camera flash (with the A550 triggering it via the flash). I'd appreciate any pointers.